As described in JP-A-2008-133421, there has hitherto been known an azo compound (dichroic dye) showing absorption dichroism in a short wavelength region (380 to 500 nm) of visible light. Such an azo compound is used for the preparation of a neutral gray polarizing film (polarizing film having averaged transmittance and averaged polarization degree in a wide visible light region of 380 to 780 nm), for example, by mixing it with a dye showing absorption dichroism in a long wavelength region (more than 500 nm to 780 nm) of visible light.
However, although the azo compound described in the above-mentioned JP-A-2008-133421 shows a relatively high dichroic ratio on the short wavelength side (380 to 500 nm) of visible light, the dichroic ratio thereof is at most about 30, and 50 or less. Thus, the dichroic ratio thereof is still low under the present situation.